Safety system for continuous casting machine

ABSTRACT

In a continuous casting machine having a curved strand guide, a flexible dummy bar, at least one driven roll, and a fluid pressure system for causing said driven roll to grip and move the dummy bar, a stopping device is located along the path of the dummy bar which is activated by a pressure drop in the fluid pressure system of the driven roll to grip and stop motion of the dummy bar.

United States Patent Schulz 1 Dec. 26, 1972 [S4] SAFETY SYSTEM FOR CONTINUOUS [56] References Cited CASTING MACHINE UNITED STATES PATENTS [72] Inventor: Hans-Dieter Schulz, Duesseldorf,

Germany 3,263,284 8/1966 Orr ..l64/282 ux 3,456,767 7/1969 l-lollnagcl ..l88/l70 Asslsnw Schloemnn Aktiensmllschafl, 3,375,862 4/1968 BOlIChOIIkO ..l64/263 x e Germany 3,442,322 5/1969 Lemper ..164/274 [22] Filed: Oct. 19, 1970 Primary Examiner-J. Spencer Overholser [2]] App! 81886 Assistant Examiner-John S. Brown Attorney-Sandoe, Hopgood & Calimafde [30] Foreign Application Priority Data 061. 22, 1969 Germany ..P 1953 094.0 [57] ABSTRACT In a continuous casting machine having a curved [52] U.S. Cl. ..164/152, 164/282, 188/170, strand guide a fl ibl dummy bar at least one driven I 43 3 38 5 3 4 33 roll, and a fluid pressure system for causing said [51] nt. driven [on to g and move the dummy bar a [58] Field of Search ..l64/152, 153, 274, 282, 70,

stopping device is located along the path of the dummy bar which is activated by a pressure drop in the fluid pressure system of the driven roll to grip and stop motion of the dummy bar.

3 Claims, 2 Drawing Figures PATENTEDumsmz INVENTOR. HANS- DIETER SCHULZ ATTORNEYS SAFETY SYSTEM FOR CONTINUOUS CASTING MACHINE The present invention relates to a safety system for a continuous casting machine and particularly for a machine having a curved strand guide and utilizing a flexible dummy bar for starting the casting operation. Prior art continuous casting machines have driven rolls which are equipped with hydraulic cylinders which cause the rolls to initially grip the dummy bar and later to grip the cast strand to feed the same. In starting a casting operation, the driven rolls grip the dummy bar and drive it upstream through the strand guide until it reaches a position where the dummy-bar head closes the mold. Ordinarily the long and'heavy dummy bar is held in this position by pressure applied by the hydraulic cylinders to the driven rolls until the casting process starts. At that time sufficient molten metal has been poured into the mold and has solidified around the dummy bar head and has also formed a solidified strand shell so that a continuously cast strand can be withdrawn from the mold by operation of the driven rolls. However, a failure in the hydraulic system releases the pressure on the drivenrolls and the flexible dummy bar, propelled by gravity, makes an uncontrolled downward movement of increasing velocity through the strand guide and the adjacent downstream equipment, thereby interrupting the casting process and damaging expensive equipment.

It is advantageous to use a flexible dummy bar in connection with curved strand casting machines, and the problem is critical in connection with such bars because, due to their flexibility, their smooth surfaces, and also due to the lubricating effect of the cooling water in the curved strand guide, there is only slight frictional resistance to sliding movement within the strand guide in the event that the pressure applied to the dummy bar by the driven rolls is relaxed due to a drop in pressure in the hydraulic system.

It is the object of the present invention to prevent such uncontrolled downward movement of the dummy bar caused by failure of the hydraulic system which applies pressure to the driven rolls.

According to the present invention, this object is obtained by providing a device along the path of the dummy bar movement which is adapted to grip and stop movement of the dummy bar in the event of failure of the hydraulic system. In the embodiment illustrated, this stopping device may be a clamping device which is responsive to and actuated by a drop in pressure in the hydraulic system.

Such a clamping device may comprise a fixed base plate mounted on the foundation below the path of movement of the dummy bar and a movable clamp plate located above the path of movement of the dummy bar opposite to the fixed plate. Springs are provided which tend to urge the upper clamp plate against the dummy bar to cause it to grip and hold the dummy bar against movement. However, means are also provided for holding the upper plate above the dummy bar against the pressure of said springs during the normal operation of the machine. Failure of the hydraulic system releases the said holding means to permit the said springs to move the upper plate to grip and hold the dummy bar.

According to the present invention, the stopping device may be activated by a pressure drop in the hydraulic system which presses the drive rolls against the dummy bar. For this purpose hydraulic cylinders are utilized as the means for holding the upper clamp plate above the dummy bar, and these cylinders are connected to the hydraulic system which generates the drive roll pressure. If this hydraulic system fails, and there is a pressure drop in the system, the pressure in the hydraulic cylinders no longer counteracts the pressure of compression springs on the clamp plate and the clamp plate is pressed downward against the dummy bar, thereby gripping it and stopping its movement.

The stopping device is preferably located downstream of the drive rolls.

The drawings show a preferred embodiment of the invention in which:

FIG. 1 is a schematic side view of a curved strand casting machine, equipped with the stopping device, and

FIG. 2 is an enlarged front view, partly in section, of said stopping device.

The curved strand continuous casting machine shown schematically in FIG. 1 is of conventional construction and comprises a tundish 1, an open-ended mold 2, a curved strand guide 3, a straightenerwithdrawal unit 4, and a strand cutting station 6. Molten metal is supplied to the tundish from a ladle 20. The straightener-withdrawal unit 4 has drive rolls 7 which are pressed against the dummy bar 5 by pressure applied by hydraulic cylinders 9, which are supplied with fluid under pressure by a pump 8. The stopping device 10 is located between the straightener-withdrawal unit 4 and the strand cutting station 6.

As shown in FIG. 2, a fixed base plate 12 is located below the dummy bar 5 between the straightenerwithdraw'al unit 4 and the roller table rolls 11. It supports two vertical columns 13, which are rigidly secured to it by nuts 14. A movable clamp plate 15 is guided on the columns 13, and nuts 16 and washers 17 located at their upper ends hold springs 18 under compression and press downwardly on the plate 15. Hydraulic cylinders 19 rest on the base plate 12 and are provided with piston rods 19' connected to the clamp plate 15.

As shown in FIG. 1, the hydraulic cylinders 19 are connected with the hydraulic system and as long as pressure is maintained in the system they are supplied with pressurized fluid by the pump 8 and counteract the pressure applied to the clamp plate 15 by compression springs 18, thereby retaining the clamp plate above the dummy bar. If the hydraulic system fails, and the pressure in the hydraulic system drops, it no longer counteracts the compression springs 18 which will then press the clamp plate 15 downward against the dummy bar to grip it and stop its movement.

I claim as my invention:

1. In a continuous casting machine comprising an open-ended mold, a curved strand guide, a flexible dummy bar, at least one driven roll for engaging and feeding said dummy bar upstream through said strand guide into said mold and for withdrawing said dummy bar when the casting operation begins, and a hydraulic system including hydraulic cylinders connected to said driven roll to apply driving pressure to said dummy bar,

a stopping device comprising a fixed plate and a movable plate located on opposite sides of said dummy bar downstream from said strand guide, said plates forming a clamping device, means to separate said plates while said hydraulic system is applying driving pressure to said dummy bar, means to close said plates to grip and hold said dummy bar upon a drop of pressure in said hydraulic system, said plate separating means comprising at least one hydraulic cylinder connected to said hydraulic system, and having a piston connected to said movable plate which is actuated by the hydraulic pressure in the system.

2. Apparatus as claim in claim 1 in which said means to close said plates comprises spring means which apply pressure to said movable plate tending to move said plate toward said fixed plate.

3. Apparatus as claimed in claim 1 in which said movable plate is slidably mounted on a pair of vertical columns, and in which said means to separate said plates comprises a pair of hydraulic cylinders, each connected to said hydraulic system and each having a piston connected to said movable plate which is actuated by the hydraulic pressure in the system, and in which said means to close said plates comprises a pair of compression springs mounted on said vertical columns and applying pressure to said movable plate tending to move said plate toward said fixed plate.

* i k i l060l2 mm. 

1. In a continuous casting machine comprising an open-ended mold, a curved strand guide, a flexible dummy bar, at least one driven roll for engaging and feeding said dummy bar upstream through said strand guide into said mold and for withdrawing said dummy bar when the casting operation begins, and a hydraulic system including hydraulic cylinders connected to said driven roll to apply driving pressure to said dummy bar, a stopping device comprising a fixed plate and a movable plate located on opposite sides of said dummy bar downstream from said strand guide, said plates forming a clamping device, means to separate said plates while said hydraulic system is applying driving pressure to said dummy bar, means to close said plates to grip and hold said dummy bar upon a drop of pressure in said hydraulic system, said plate separating means comprising at least one hydraulic cylinder connected to said hydraulic system, and having a piston connected to said movable plate whicH is actuated by the hydraulic pressure in the system.
 2. Apparatus as claim in claim 1 in which said means to close said plates comprises spring means which apply pressure to said movable plate tending to move said plate toward said fixed plate.
 3. Apparatus as claimed in claim 1 in which said movable plate is slidably mounted on a pair of vertical columns, and in which said means to separate said plates comprises a pair of hydraulic cylinders, each connected to said hydraulic system and each having a piston connected to said movable plate which is actuated by the hydraulic pressure in the system, and in which said means to close said plates comprises a pair of compression springs mounted on said vertical columns and applying pressure to said movable plate tending to move said plate toward said fixed plate. 